FORT MYERS, Fla. -- It was Aug. 31, 2014, a typically stifling summer Saturday in Florida. Clay Buchholz had just finished off a 98-pitch, three-hit shutout of the Tampa Bay Rays, one of the best pitching performances of the season for the Boston Red Sox.

And nobody cared.

Most team officials were preoccupied by a handful of at-bats 120 miles south of Tropicana Field. In Fort Myers, at the Red Sox's training facility, Rusney Castillo was playing his first minor league game since signing a seven-year, $72.5 million contract, the largest deal ever for a Cuban defector.

Still feeling the sting of finishing second to the Chicago White Sox in the bidding for Cuban slugger Jose Abreu, the Red Sox went all out for Castillo, convinced he would follow countrymen Yoenis Cespedes, Yasiel Puig and Abreu to big league stardom. One team official even compared the outfielder's athleticism to Deion Sanders.

Thirty months later, Castillo has gone from the next Puig to purgatory.

Three years after signing a $72.5 million deal, Rusney Castillo is an afterthought in camp after failing to meet the lofty expectations put on him. Steve Mitchell/USA TODAY Sports

Castillo is in camp with the Red Sox, but he isn't really here. He doesn't stand a chance to make the team. Not after batting .262 with a .301 on-base percentage and .679 OPS in 337 career plate appearances and winding up in Triple-A for most of last season. And not with Mookie Betts, Jackie Bradley Jr. and Andrew Benintendi combining to form one of the best young outfields in baseball and Chris Young providing the perfect veteran presence off the bench.

The Red Sox would consider trading Castillo, but that's problematic, too. Having removed him from their 40-man roster last season, they almost certainly would have to sweeten any deal by paying a portion of the $46 million remaining on his contract. But that would count against their luxury-tax bill, which is a nonstarter given the Red Sox's desire to stay below the $195 million threshold this season.

"You know there are some things that you can't control, and at the end of the day, your hard work is what speaks for you," Castillo said Sunday through a team interpreter. "I'm just looking forward to putting the past behind me and working hard now so that people can see exactly who I am."

Castillo hasn't been anything close to the player the Red Sox expected. At the plate, his approach remains unrefined. He has been vulnerable to even medium-velocity fastballs and doesn't reach base nearly enough to use his speed. Defensively and on the bases, Castillo often has demonstrated questionable instincts.

It all might be easier to bear if Castillo was 21. But he turns 30 in July, making it less likely that he will suddenly figure everything out.

"His age is certainly not a plus," said Red Sox senior vice president of player personnel Allard Baird, who scouted Castillo extensively and made a strong recommendation to sign him. "However, his makeup, along with a strong work ethic, has never left him. Our hope is that he performs up to his potential this season."

Castillo had a strong winter ball season in Puerto Rico, batting .392 in 51 at-bats for a team managed by former big league infielder Alex Cora, one of his biggest supporters since he signed with the Red Sox. Castillo said he worked on making his swing shorter and more compact.

There's another difference for Castillo. Several family members, including his son, have finally been able to join him in the United States. Rusney Jr. turns 5 in April.

"It's been a huge difference for me having them here," Castillo said. "I think that's a big reason why I had so much success in winter ball, because I had them there. For a couple years now, I've been stressed that they weren't here. So now that I have them here, it's been huge for me personally."

If it hasn't already, time is running out for Castillo to make the big impact the Red Sox believed he would.

"My goal is to continue working and do my job, whether that be in Triple-A or the majors," Castillo said. "Obviously the goal is to get to the major leagues. But if I start in Triple-A, that doesn't change how hard I'm going to work to get to where I want to go."